Certain areas, e.g., on a road in front of a vehicle, are frequently scanned for various situations by means of radar in order to collect information and to make it available for further processing. In EP 1 431 773 A2 an angle-scanning radar system is described in which an array antenna is provided that is controlled via a beam-forming network. A coupling unit enables the operation of the array antenna for the transmitting and receiving device. Separate sensitivities are set for various angle sections in order to detect objects with angular resolution. The radar system serves, thereby, as vehicle assistance.
Active antennas are able to change their radiation pattern electronically in order to be able to track objects from moveable platforms, such as from vehicles. For antennas with digital beam-forming, the radiation pattern can, in addition, be adapted to the surroundings, and several radiation lobes are produced in order to establish the connection to several remote stations simultaneously, as well as to suppress jamming transmitters by zero adjusting in the directional diagram (see http://elib.dir.de/22932/). An antenna with electronic deflection is known from DE 196 38 149 A1. The deflection is achieved through controlled phase shifters. Establishing the phase shifting enables the directional diagram to turn in each desired direction within a two-dimensional angular range.
The Rotman lens, or the Butler matrices, are known as so-called beam-forming networks (http://scholar.lib.vt.edu/theses/available/etd-04262000-15330030/unrestricted/ch3.pdf). DE 196 38 149 A1 enumerates other electromagnetic lenses. The Rotman lens, or Butler matrices, have been used up to now for continuously sinusoidal or pulsed sinusoidal high-frequency signals (pulse radar, CW radar), whose frequency bandwidth comprises max. one octave (e.g., 1-2 GHz).
The article on the Internet at the Internet site http://copernicus.org/URSI/kh tagung/2000/abstracts/ccc0049.pdf deals with the development of a Rotman lens at 94 GHz for controlling an antenna row. The lens designed in the W band at 94 GHz includes 13 input ports for an angle range of ±30° in steps of 4.8°, as well as 20 output ports for controlling the 20 antenna elements.
In particular, with very short-duration rapidly rising pulses, for example, in the range of some 10 to 100 picoseconds, a time variation at triggering is necessary and, if possible, below ¼ of the rise time. This is only possible with absolutely stable runtimes of the system with high thermal stability, or the like effort. Furthermore, at a pulse repeat rate of, for example, 100 kHz, control of the beam from pulse to pulse is difficult to implement with this high resolution in terms of time. If the entire system, or the individual modules, is/are rotated mechanically, then a very high mechanical angular velocity is necessary.
The object of the invention is to disclose a control of a radiation main lobe with very precise spatial resolution in row and/or slot.